Microbeads utilizing hydrogel (Advanced Materials, 19, pp. 2696, 2007; Lab on a Chip, 8, pp. 259, 2008) and microfibers utilizing the same (Lab on a Chip, 4, pp. 576, 2004; Langmuir, 23, pp. 9104, 2007; Lab on a Chip, 8, pp. 1255, 2008) have been focused because of their applicability to researches on cells and proteins. In particular, microfibers utilizing hydrogel as a base material are useful for construction of biochemical sensors (Lab on a Chip, 4, pp. 576, 2004) and artificial tissues (Langmuir, 23, pp. 9104, 2007; Lab on a Chip, 8, pp. 1255, 2008), and are expected to be useful to construct a woven fabric structure and thereby produce a complicated three-dimensional structure having a large area.
Among microfibers comprising hydrogel, microfibers comprising alginate gel as a base material have sufficient mechanical strength. However, microfibers prepared from other hydrogel materials (for example, microfibers comprising peptide hydrogel) have a problem that they are weak in mechanical strength, and cannot be used for producing woven fabrics having a microstructure. From such points of view, means for improving strength of microfibers, those utilizing hydrogels other than alginate gel as a base material, has been highly desired.